The super-star cluster NGC 1569-A resolved on subparsec scales with HubbleSpace Telescope spectroscopy

We present 3000-10000 Angstrom Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph long-slit spectroscopy of the bright super-star clust er A (SSC-A) in the dwarf starburst galaxy NGC 1569. The 0."05 HST angular resolution allows us, for the first time, to probe for spatial variations i n the stellar population of an similar to 10(6) M-. SSC. Integrated ground- based spectra of SSC-A have previously revealed young Wolf-Rayet (W-R) sign atures that coexist with features from supposedly older, red supergiant (RS G) populations. We find that the W-R emission complexes come solely from th e subcluster A2, identified in previous HST imaging, and are absent from th e main cluster A1, thus resolving the question of whether the W-R and RSG f eatures arise in a single or distinct clusters. The equivalent widths of th e W-R features in A2-including the C iv lambda 5808 complex that we detect in this object for the first time-are larger than previously observed in ot her W-R galaxies. Models with subsolar metallicity, as inferred from the ne bular emission lines of this galaxy, predict much lower equivalent widths. On the "clean" side of A1, opposite to A2, we find no evidence for radial g radients in the observed stellar population at 0."05 < R < 0."40 (similar t o0.5-5 pc) in broadband, low-resolution spectra or in medium-resolution spe ctra of the infrared Ca II triplet.